Housing prices across China rose 6.4% in May, the fastest year-on-year increase in 18 months, prompting the government to investigate "abnormal factors" behind the reports of rapid growth, the South China Morning Post reported. In Beijing, housing prices rose 10.4% that same period. Shenzhen's residential property prices saw the sharpest spike, at 12.3%. "Given the current market situation and the government's attempts to slow housing price rises, this increase is really shocking," said Jason Yang of Colliers International in Beijing, the Financial Times reported. The government is expected to raise interest rates twice before the end of this year to curb further growth.